Preston Hughes, who has been on death row for 23 years for fatally stabbing a teenage girl and a toddler, is suing the state of Texas over the drug it plans to use to execute him in November, claiming officials are "experimenting" on him and other inmates.

Hughes, 46, is arguing that prison officials, facing a shortage of drugs for the three drug "cocktail" formerly used for lethal injection, did no medical testing before changing the protocol to using a single drug, according to court records.

"They are experimenting on death row inmates because there's never been any kind of medical review, that we know about, that this is a humane way to carry out their legal function," said Pat McCann, one of Hughes' attorneys. "I'm not saying they can't execute people. I'm saying they ought to give it more thought than the time it takes to play a round of golf."

Officials with the Texas Department of Criminal Justice declined to comment on the pending lawsuit, but said agency officials examined the execution procedures in other states before changing the procedure.

"The one drug protocol has been adopted by several states and has been upheld as constitutional by the courts," spokesman Jason Clark said in a statement.

Single, lethal dose

The execution protocol was changed from a three-drug sequence to a single, lethal dose of pentobarbital in July because TDCJ's stock of the second drug expired and it couldn't get more.

Anti-death penalty groups have for years been pressuring drug companies, especially in Europe, to stop making or selling drugs used in executions.

Since July, three Texas inmates have been executed using one drug.

No testing

The new procedure, McCann said, was put in to effect without any tests.

"They changed the cocktail, fairly dramatically, because they could get it on sale and stockpile it," McCann said. "But they're not doctors and they're not entitled to experiment on my client."

He said TDCJ did not seek out opinions from any professional in the medical, psychiatric, or psychological fields about whether the new drug would be "cruel and unusual punishment."

"There is some merit to the claim that it is experimenting," Dieter said. "In the medical field, you would want experts weighing in on what the best protocol would be."

However, he said, the standard to get a stay of execution is a high hurdle.

"The U.S. Supreme Court has said you have to show a substantial risk of serious pain, not just allege there may be problems," Dieter said. "There is some merit to the claim, but it's an ethical claim. Legally, it may have some trouble."

Hughes is scheduled to be executed Nov. 15 for fatally stabbing a teenage girl and a 3-year-old boy in September 1988.